
import {
	Blob,
	btoa,
	createImageBitmap,
	CSSStyleDeclaration,
	performance,
	document,
	DOMParser,
	EventTarget,
	fetch,
	Headers,
	HTMLCanvasElement,
	Image,
	HTMLImageElement,
	ImageBitmap,
	location,
	navigator,
	Request,
	requestAnimationFrame,
	cancelAnimationFrame,
	Response,
	URL,
	window,
	self,
	WebAssembly,
	Worker,
	XMLHttpRequest,
	ImageData,
	TextDecoder,
	core
	} from 'dhtml-weixin';
/**
 * RGB Shift Shader
 * Shifts red and blue channels from center in opposite directions
 * Ported from https://web.archive.org/web/20090820185047/http://kriss.cx/tom/2009/05/rgb-shift/
 * by Tom Butterworth / https://web.archive.org/web/20090810054752/http://kriss.cx/tom/
 *
 * amount: shift distance (1 is width of input)
 * angle: shift angle in radians
 */

const RGBShiftShader = {

	name: 'RGBShiftShader',

	uniforms: {

		'tDiffuse': { value: null },
		'amount': { value: 0.005 },
		'angle': { value: 0.0 }

	},

	vertexShader: /* glsl */`

		varying vec2 vUv;

		void main() {

			vUv = uv;
			gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );

		}`,

	fragmentShader: /* glsl */`

		uniform sampler2D tDiffuse;
		uniform float amount;
		uniform float angle;

		varying vec2 vUv;

		void main() {

			vec2 offset = amount * vec2( cos(angle), sin(angle));
			vec4 cr = texture2D(tDiffuse, vUv + offset);
			vec4 cga = texture2D(tDiffuse, vUv);
			vec4 cb = texture2D(tDiffuse, vUv - offset);
			gl_FragColor = vec4(cr.r, cga.g, cb.b, cga.a);

		}`

};

export { RGBShiftShader };
